It has been reported that in some articles, URLs get replaced with [#########] characters.
After some testing by @Pajz, it seems like OTRS' URL formatting breaks when, despite shortening the URL, it still doesn't fit in one line (lines in notes have a fixed width) because the URL is part of a long string. This looks like a non-issue for Western languages because words/symbols/URLs are separated from other words/symbols/URLs by empty spaces, so there's no good reason why the URL wouldn't fit in one line: OTRS always shortens the URL to a length that fits comfortably in one line, and there should always be a breaking space very close to the <...> brackets. But it's apparently a problem in Japanese because it seems normal there that a URL would directly follow (many) other characters (without an empty space next to it)